textview显示跑马灯效果，使用的是继承的方法onDraw不停地绘制 

优点： 

1.文字长短不限哦 

2.不用非得获取焦点哦　　

 

package feng.f7_27.activity;import android.content.Context;import android.graphics.Canvas;import android.graphics.Paint;import android.os.Parcel;import android.os.Parcelable;import android.util.AttributeSet;import android.view.Display;import android.view.View;import android.view.View.OnClickListener;import android.view.WindowManager;import android.widget.TextView;public class CustomTextView extends TextView implements OnClickListener{    public final static String TAG = CustomTextView.class.getSimpleName();    private float textLength = 0f;//�ı�����    private float viewWidth = 0f;    private float step = 0f;//���ֵĺ����    private float y = 0f;//���ֵ������    private float temp_view_plus_text_length = 0.0f;//���ڼ������ʱ����    private float temp_view_plus_two_text_length = 0.0f;//���ڼ������ʱ����    public boolean isStarting = false;//�Ƿ�ʼ����    private Paint paint = null;//��ͼ��ʽ    private String text = "";//�ı�����    public CustomTextView(Context context) {    super(context);    initView();    }    public CustomTextView(Context context, AttributeSet attrs) {    super(context, attrs);    initView();    }    public CustomTextView(Context context, AttributeSet attrs, int defStyle) {    super(context, attrs, defStyle);    initView();    }    /** *//**    * ��ʼ���ؼ�    */    private void initView()    {    setOnClickListener(this);    }    /** *//**    * �ı���ʼ����ÿ�θ���ı����ݻ����ı�Ч���֮����Ҫ���³�ʼ��һ��    */    public void init(WindowManager windowManager)    {    paint = getPaint();    text = getText().toString();    textLength = paint.measureText(text);    viewWidth = getWidth();    if(viewWidth == 0)    {    if(windowManager != null)    {    Display display = windowManager.getDefaultDisplay();    viewWidth = display.getWidth();    }    }    step = textLength;    temp_view_plus_text_length = viewWidth + textLength;    temp_view_plus_two_text_length = viewWidth + textLength * 2;    y = getTextSize() + getPaddingTop()+15;    }    @Override    public Parcelable onSaveInstanceState()    {    Parcelable superState = super.onSaveInstanceState();    SavedState ss = new SavedState(superState);    ss.step = step;    ss.isStarting = isStarting;    return ss;    }                            @Override    public void onRestoreInstanceState(Parcelable state)    {    if (!(state instanceof SavedState)) {    super.onRestoreInstanceState(state);    return;    }    SavedState ss = (SavedState)state;    super.onRestoreInstanceState(ss.getSuperState());    step = ss.step;    isStarting = ss.isStarting;    }    public static class SavedState extends BaseSavedState {    public boolean isStarting = false;    public float step = 0.0f;    SavedState(Parcelable superState) {    super(superState);    }    @Override    public void writeToParcel(Parcel out, int flags) {    super.writeToParcel(out, flags);    out.writeBooleanArray(new boolean[]{isStarting});    out.writeFloat(step);    }    public static final Parcelable.Creator
     
       CREATOR    = new Parcelable.Creator
      
       () {    public SavedState[] newArray(int size) {    return new SavedState[size];    }    @Override    public SavedState createFromParcel(Parcel in) {    return new SavedState(in);    }    };    private SavedState(Parcel in) {    super(in);    boolean[] b = null;    in.readBooleanArray(b);    if(b != null && b.length > 0)    isStarting = b[0];    step = in.readFloat();    }    }    /** *//**    * ��ʼ����    */    public void startScroll()    {    isStarting = true;    invalidate();    }    /** *//**    * ֹͣ����    */    public void stopScroll()    {    isStarting = false;    invalidate();    }    @Override    public void onDraw(Canvas canvas) {    canvas.drawText(text, temp_view_plus_text_length - step, y, paint);    if(!isStarting)    {    return;    }    step += 0.5;    if(step > temp_view_plus_two_text_length)    step = textLength;    invalidate();    }    @Override    public void onClick(View v) {    if(isStarting)    stopScroll();    else    startScroll();    }}
      
     

tv.setText("aaaaaavvv");        tv.init(getWindowManager());        tv.startScroll();